Expansible rotary drill bit



Patented Oct. 6, 1953 UNITED STATES ram OFF EXPANSIBLE ROTARY DRILL BITArcher W. Kammerer, Fullerton, Calif. Application August 18, 1950,Serial No. 180,168

9 Claims. 1

The present invention relates to rotary drill bits, and moreparticularly torotary drill bits of the type embodying cutters that areshiftable between retracted and expanded positions, to drill a holebelow a casing string larger in diameter than the inside diameter of thecasing string through which the bit is lowered.

In my prior Patent 2,466,991, a rotary drill bit is disclosed havingcutters that are expanded outwardly to their full enlarged drillingdiameter before any drilling weight is imposed on the cutters. Aftertheir expansion, a downward thrust on the drilling string locks thecutters in their outward expanded position and prevents theirretraction.

The type of lock device disclosed in the above patent may urge thecutters outwardly from retracted, or partially retracted, positions inthe event drilling weight is imposed on the bit before the cutters havebeen expanded to their maximum position. The operator may not be advisedof the fact that the cutters have not been moved to their maximumexpanded position, since the Wedging or expanding force imposed on thecutters would enable them to support the drilling weight. Accordingly,the lock device would be the instrumentality for expanding the cutters,which would result in the imposition of loads on such lock device thatthe preferably should not carry. Moreover, an undergauged hole might beproduced along a certain length of the well bore.

In certain types of hole enlarging operations, such as the increasing ofthe well bore size along only a portion of its length, the cutters maybe pulled upwardly into a relatively small diameter Well bore portion,as would occur in the event the kelly at the top of the hole were to beremoved from the drill string. Thereafter, upon reconnecting the drillpipe and kelly, and lowering of the drill string and bit, the lockdevice might tend to urge the cutters outwardly in the smaller diameterhole, merely as an incident of the lowering movement of the drill stringfor the purpose of relocating the bit back into the enlarged portion ofthe well bore. Such premature outward expansion of the cutters is notdesired.

Accordingly, it is an object of the present invention to provide a lockdevice which does not tend to expand the cutters outwardly, at leastuntil such cutters have been expanded to a substantial extent by someother means.

Another object of the invention is toprovide a locking arrangement in anexpansible rotary drill bit which will exert substantially no outwardexpansive force on the cutters until after they have moved outwardlybeyond a predetermined hole drilling diameter, but which can thereafterforcibly urge the cutters outwardly to their maximum hole drillingdiameter.

A further object of the invention is to preclude any downward forcesimposed on an expansible rotary drill bit by the drill string fromurging the cutters outwardly, unless such cutters have previously beenexpanded beyond a certain hole drilling diameter; so as to offerassurance that the cutters would be resting upon a substantial formationshoulder in the well bore before any appreciable drilling weight can beimposed upon them. Because of the arrangement noted, the downwarddrilling weight would merely slide the entire tool down the hole withoutenlarging the latter, in the event that the cutters are in theirsubstantially fully retracted position.

This invention possesses many other advantages, and has other objectswhich may be made more clearly apparent from a consideration of a Figure1 is a longitudinal section through an expansible rotary drill bitdisposed within a well bore, with the parts of the drill bit inretracted position for lowering in the well bore;

Fig. 2 is a view similar to Fig. 1 of the drill bit, with its parts intheir fully expanded'position;

Fig. 3 is an enlarged somewhat diagrammatic view through the lockport-ion of the bit, with a cutter in fully retracted position;

Fig. 4 is a View similar to Fig. 3, illustrating the locking devicepreventing retraction of a cutter from its maximum outward expandedposition;

Fig. 5 is a view similar to Fig. 3, illustrating the coaction betweenthe lock device and the cutter device when the latter occupiesintermediate positions between its fully retracted and fully expandedpositions.

As shown in the drawings, the expansible rotary drill bit A is attachedto a string of drill pipe B by means of which it is lowered in the wellbore to the point at which enlargement of the bore hole is to commence.The bit is capable of enlarging the bore hole by producing and operatingupon a formation shoulder C, as hereinafter described.

The upper end of the bit consists of a driving mandrel I I whose upperpin I2 is threadedly connected to a sub I3, forming the lower end of thedrill pipe string B. This mandrel includes an upper kelly or drill stemmember I4 slidably splined to. the main ..body I5 of. the bitin anysuitable manner, suchaszdisclosediin my Patent 2,466,991. The mandrel I4has a limited'range of longitudinal movement within the body, its.upward movement being determined by engagement of an external shoulderH1: their-kelly; with a retainer ring I! suitably secured to the upperend of the body I5, as by the'us'e of weldirlg material I8.

The body [5 has a plurality of expansible parts mounted on it,comprising opposed cutter-sup porting members I9, I9 pivotally carriedon pivot or hinge-pins 2 21' suitably'secured:to the body: Each cuttersupporting member: consists; oh a; depending leg 23havinga:bearingsupportingipin: 24 inclined inwardly and dhwnwardly' and:on". which is rotatablymounted'ia roll'er side cutter 2'5. Anti-frictionroller and. ball-bearing e1e+- ments 26 21 arepreferably"placedzbetweenieach: cutter 25 and bearing pin 211;therroller bearings 26- transmitting: radialv thrusts; and the ball"bearings 21 both radial and axial thrusts.

Each cutter supporting: member, i=9" also ine cludes' an upwardlyextending: arm 30' against which an elastic expander 31f bears: Thisex.- pan'der is in'the'form of: a c'ompressed coil spring receivedwithin a retainerpocket 32 in the body I5, exerting its forceagainst thearm. 30 and tending to swing'it inwardly and :thus: urgethe. cutter 25on the other side. of the: fulcrum pin: 2| in an outward direction. Theextent of this: outward movement-is limited lay-engagement of stopshoulders 33; 33. on oppositezsides: of. the. cutter supporting: member:[.9 with cooperable body stopshoulders: 34;:34;

After. each cutter 25' has" been expande'dqoutr wardly by its cooperableexpander'spr-ing-ifirltoi 5;) the maximum extent, it-:cane be lcckedin.this position by a tubular member: 35' of the mandrel. I I, which ispiloted in the kelly l'flrandsisprovided. witha lock portion e1.Ehelatter is; movable; from an upper positionin transverse alignmentwith inner supporting member recessespafi perv mitting retraction of thecutters; to: alowerposition opposite lugs-'31. formed: on and projectinginwardly from the supporting member: legs: 23; preventingqretraction ofthe-cutters 25.

The tubular member 35- is connected; in. swivel fashion to the kelly [4to permit relative arcuate or rotary movement therebetween. However. thekelly and tubular member are movable together for longitudinal movement.in-both direc-- tions. All this is accomplished by providing a shoulder56 on the tubular member containing an external toroidal raceway 51receivingbearing balls 38 that are also ridable in an opposed; internalraceway 39 formed in the kelly I4. The balls 33 are insertable through ahole 46 extending through the kelly shoulder" I5, and, after having beenmounted in place within. theraceways 57, 39, this hole can be closed bya suitable: plug 4! which is prevented from moving out of the hole bythe main body I5 of the bit.

The upper portion 35a of the tubular member 35 is piloted within thefluid passage 42 through the kelly I I, and has itsend'3'5b flaringupward.- ly and outwardly to. guide a. ball 4.3,. or .ecrra spondingelement, into the central passage 350 through the tubular member 35.Fluid pumped down the drill string B will flow through the kelly pin [2and into the central passage 350. It is prevented from flowing aroundthe exterior of the tubular member 35 by a suitable packing 44 disposedbetween the upper portion 35a of the tubular member and the kelly It;adjacent the upper end of the tubular member shoulder 55.

The arrangement betweenlthe tubular member 35 and kelly I4" is such"that" both downward and upward movement is transmitted between the kellyI4 and tubular member 35 from one racewayilon 39, through the ballbearing elements 38', to the other raceway 39 or 51. In this theakellyI4 and tubular member 35 are caused to mo.vel iointly in bothlongitudinal directions, but they are able to partake freely oirelativamovement therebetween.

The mandrel II is normally held in its upper positionwith respect tothemainbody I5..of the bitiand the supporting; membersl I9. by a.helical, retractor spring 46 encircling the tubular member. 35, with.its. upper. end. engaging. the. mandrel.

shoulder strand its: lower endengaging aspring, seatAB resting onthebody If. This spring seat.

is also serves as anupperbearing guide forv the tubular mandrel. member35,. whose lower. end is slidable withina lower. bearing guide 49, belowthe lugsv 31,- which. isv integral. with. or secured. to the mainbodyof. thebit. The, two guides. 48,. dilform aspaceditwo-poi'nt supportfor the mandrel" member 35T'and' assist it inresisting. inward movementofjthelcutter legs, Z3v toy I retracted position during the reaming orcutting operationl Circulatingfl'uid canpass downwardly through thestringof drill pipe B and through the -tubular mandrel. II; forei'ectionfrom it'sl'ower discharge nozzle 35d and. onto the cutters, 2,5, tocleanse. them of cuttings. and. flush thev latter from the. drillingarea to thetopot the wellbore. This circulating fluid. is also availedv011$ to unlatch the cutter. supporting,.members I'BLin the. event it isdesiredto hol'djthem positively in re tractedposition.

The cutters may be retained initially in ret'racted, positions againstthe, expansive forces of the springs 3| by meanso a trip device deviceincludes a holding plate or member '18 secured to, the lower end'of acentral rod" whoseupper; end projects into the tubularmember passage350.. Ahead is secured to the upper end of the rod, which hassubstantial clearance there-around, in order ta allow fluids to passupwardly into the central passag 35c and into the drill string B, Theholding member I8 has spaced holes 82. in its outer portion forreceiving the lower ends 29a of ball. bearing plugs or pins 2'9 whichhold the cutter bearing balls 21 in operative position.

When the holding device it is disposed over the pins 29, the cuttersupporting members I9 are prevented from expanding under the influenceof the springs 35-, thereby holding the cutters 25" in retractedposition. It isto be noted that the pins 29' are inclined initially in adownward and outward direction, so as to prevent the holding member 18and the rod 19' connected thereto from moving downwardly until purposelyreleased, which downward movement would allow outward, expansion of thecutters 25. Such: release can occuras a result of fluid pressure-actingdownwardly on the'ball 43, which can rest on.

the head 80.

.Durineloweringoithtin ttina tool tozthe point This 1 at which thereaming operation is to begin, the holding device I8, I9 retains thecutters 25 in retracted position. During this lowering operation, fluidmay flow upwardly around the holding device rod 79 and around the head80 into the tubular member passage 350.

When the point in the well bore has been reached at which the reamingoperation is to begin, the pumps at the top of the well bore are startedand drilling fluid pumped down the drill string B. The ball is thenforced down through the passage 35c onto the head 89. Since the diameter of the ball is preferably equal to the diameter of passage 350,it substantially closes the passage to downward flow of fluids, whichallows the pumps at the top of the well bore to exert a pressure on thefluid in the drill string B and tubular member. This pressure actsdownwardly on the ball 15, which correspondingly exerts a downward forceon the holding device I9, 18, shifting the latter in a downwarddirection off the pins 29, and the ball 75 and rod 1!! completely out ofthe passage 350. The pins 29 are thereby released, allowing the springs31 to expand the cutters 25 outwardly, while at the same time thepassage 350 is free from restrictions, which allows fluid to be pumpedthrough its lower nozzle 35d onto the cutters.

In the operation of the device, the tool A is mounted on the lower endof the drill string B, with its parts held in retracted position by thelatch or trip device l8, #9, as shown in Fig. 1. In this position ofoperation, the compressed retractor spring (it holds the mandrel H andits kelly It in an upward position with respect to the body I5, asdetermined by engagement of the kelly shoulder It with the body retainerring l7. With the mandrel in this position, its lock portion 41 iselevated above the lugs 37 on the cutter supporting members within theinner recesses 36 in the supporting members, which permits the latter tobe held inwardly against the action of the expander springs 3|.

The tool is lowered through the well casing, and upon reaching theposition in the well here at which the drilling operation is to begin,the pumps are started at the surface of the well bore, the fluid underpressure in the drill string and bit A forcing the trip device 73 off thpins 29, releasing the cutter supporting members I9 for outwardexpansion under the influence of the springs 3|.

The drill string B is then rotated to rotate the main bit body I5through the splined .kelly and body connection, the expander springs 3iforcing the arms 3!! inwardly and the cutters 25 outwardly against theformation. Rotation is continued without moving the drill stringlongitudinally until the side cutters 25 enlarge the diameter of thehole to the maximum extent, as determined by the eventual abutting ofthe supporting member stop shoulders 33 with the companion body stopshoulders 3 Thereafter, the drill string is lowered to cause theformation shoulder C, produced in the well bore by the cutters 25 underthe action of the expander springs 3|, to support the cutter members I9and body I5, and prevent their downward movement.

Since the body I5 cannot move downwardly, drilling weight imposed on thedrilling string 13 shifts its connected mandrel I I downwardly withinthe body I5 against the action of the re- I9, being received i tractorspring 45 until the lower end 5t of the kelly I4 engages the upperspring seat and guide 48. This downward movement also shifts the tubularmember 35 downwardly, because of the interlocking ball thrust bearing31, 33, 39, to position the mandrel or tubular member lock portionopposite and in alignment with the lugs 31 on the inner portions of thecutter supporting members I9, providing a positive look by preventinginward movement of the cutters. So long as down weight is imposed on thedrill string B, and the cutters 25 rest on the formation shoulder O, thecutters are prevented from moving inwardly by engagement of their lugsa? with the mandrel lock portion 41. It is also to be noted that furtheroutward movement of the cutters beyond the predetermined maximum reamingdiameter is prevented by contact between the supporting member shoulders33 and the body shoulders 34, through which the drilling weight istransmitted to the roller cutters 25, thus relieving the hinge pins 2|of this load.

Drilling is continued by rotating the drill bit and imposing the properdrilling weight on the cutters to cause their removal of the formationmaterial and reaming of the hole in a downward direction for the desiredextent or length. When the drill bit is to be retracted and removed tothe top of the well bore, all that need be done is elevate the drillstring B, which moves the side cutters 25 above the formation shoulderC, and permits the retractor sprin 46 to press downwardly on the body I5and move it, together with the cutter supporting members I9, downwardlywith respect to the mandre1 II. This action re-positions the mandre1lock portion Ill opposite the supporting member recesses 35 and abovetheir lugs 31, because of the ball bearing coupling 38, permittinginward swinging of the cutters 25 and their supporting mem bers I9 whenthe tool passes back into a well casing (not shown), upon elevation ofthe drill string 13. The cutters 25 and their supporting members I awill ride the wall of the casing during elevation of the string untilthe tool is removed from the top of the well bore.

As noted above, after the springs 3I have expanded the cutters 25outwardly to their full hole enlarging position, the mandrel II can belowered to dispose the lock portion 4'! behind and in alignment with thecutter s pporting member lugs 37!. The outer surfaces 41a on the lockportion of the mandrel will en age the inner surfaces 37a on the lugs,to preclude retraction of the cutter supporting members I9 and theirroller side cutters 25. These surfaces 41a, 31a are preferably flat, andmay be substantially parallel to the axis of the drill bit. However, itis preferred that the outer lack or retainer surfaces lla on the lockportion of the mandrel and companion inner surfaces 31a on the lugs 31?,when the cutters are in their maximum outwardly expanded. position, beinclined slightly to the vertical, converging toward the axis of thedrill bit in a downward direction. Such slight tapering will result in aslight wedging action of the mandrel lock portion 4? within the cuttersupporting members I9, and will. tend to hold the retainer surfaces 41a,31a snugly in engagement with one another, thereby avoiding play orlooseness between the parts.

Before the springs 3| have expanded the cutters outwardly from theirinitial retracted positions to a substantial extent, any down weight ordrilling weight imposed on the drillin string B and; the mandre1 IIcannot have any effect retainer means in holding engagement with saidcutter means, said contactable port-ions, when in contact with eachother, being positioned relative to each other such that the resultantforce exerted between the portions extends in a direction parallel tothe axis of said mandrel, whereby said contacting portions do not urgesaid outter means outwardly.

2. In a rotary well drilling bit: a main body; cutter means mounted onsaid body and having an abutment member; means engaging said outtermeans for expanding said cutter means laterally outward; a mandrelslidably splined to said body and adapted for connection to a drillstring; a retainer member on said mandrel movable with said mandrel inone longitudinal direction along said body into holding engagement withsaid abutment member to prevent inward movement of said cutter meansfrom its outward expanded position; said retainer member and abutmentmember having portions contactable with each other, prior to fulllateral outward movement of said cutter means, to preclude location ofsaid retainer member into holding engagement with said abutment member,said contactable portions, when in contact with each other, beingpositioned relative to each other such that the resultant force exertedbetween the portions extends in a direction parallel to the axis of saidmandrel, whereby said contacting portions do not urge said cutter meansoutwardly.

3. In a rotary well drilling bit: a main body; cutter means mounted onsaid body and having an abutment member; means engaging said cuttermeans for expanding said cutter means laterally outward; a mandrelslidably splined to said body and adapted for connection to a drillstring; a retainer member on said mandrel movable with said mandrel inone longitudinal direction along said body into holding engagement withsaid abutment member to prevent inward movement of said cutter meansfrom its outward expanded position; said retainer member having a lowertransverse surface substantially normal to the axis of said mandrel andengageable with an upper portion of said abutment member which isinclined in an inward and upward direction.

4. In a rotary well drilling bit: a main body; cutter means mounted onsaid body; a mandrel slidably splined to said body and adapted forconnection to a drill string; means engaging said cutter means forexpanding said cutter means laterally outward independently of movementof said mandrel along said body; retainer means on said mandrel movablein one longitudinal direction along said body into holding engagementwith said cutter means for preventing inward movement of said cuttermeans from its outward expanded position; said retainer means and cuttermeans having portions contactable with each other, prior to full latera1outward movement of said cutter means, to preclude location of saidretainer means in holding engagement with said cutter means, saidcontactable portions, when in contact with each other, being positionedrelative to each other such that the resultant force exerted between theportions extends in a direction parallel to the axis of said mandrel,whereby said contacting portions do not urge said cutter meansoutwardly; said retainer means and cutter means having expander portionswhich are contactable with each other after partial lateral outwardmovement of said cutter means and prior to full lateral outward movementof said cutter means to urge said cutter means outwardly uponlongitudinal movement of said retainer means along said body towardholding engagement with said cutter means; said expander portions beingremoved from the location of contact between said other contactableportions of said retainer means and cutter means.

5. In a rotary well drilling bit: a main body; cutter means mounted onsaid body and having an abutment member; means engaging said outtermeans for expanding said cutter means laterally outward; a mandrelslidably splin d to said body and adapted for connection to a drillstring; a retainer member on said mandrel movable with said mandrel inone longitudinal direction along said body into holding engagement withsaid abutment member to prevent inward movement of said cutter meansfrom its outward expanded position; said retainer member and abutmentmember having portions contactable with each other, prior to fulllatera1 outward movement of said cutter means, to preclude location ofsaid retainer member into holding engagement with said abutment member,said contactable portions, when in contact with each other, beingpositioned relative to each other such that the resultant force exertedbetween the portions extends in a direction parallel to the axis of saidmandrel, whereby said contacting portions do not urge said cutter meansoutwardly; said members having coengaging expander portions removed fromthe location of contact between said contactable portions for urgingsaid cutter means outwardly, said expander portions being engageablewith each other only after said cutter means has been partiallyexpanded.

6. In a rotary well drilling bit: a main body; cutter means mounted onsaid body and having an abutment member; means engaging said outtermeans for expanding said cutter means laterally outward; a mandrelslidably splined to said body and adapted for connection to a drillstring; a retainer member on said mandrel movable with said mandrel inone longitudinal direction along said body to place a longitudinalsurface of said retainer member behind said abutment member to preventinward movement of said cutter means from its full outward expandedposition; said retainer member having a lower transverse surfacesubstantially normal to the axis of said mandrel and engageable with anupper portion of said abutment member which is inclined in an inward andupward direction; said abutment member having an expander surfaceinclined in a downward and inward direction and leading away from theupper portion of said abutment member to be engaged by said retainermember to urge said cutter means outwardly when said cutter means hasbeen par tially expanded by said expander means.

'7. In a rotary well drilling bit: a main body; cutter means mounted onsaid body and having an abutment member, said abutment member having anupper outer surface inclined in an inward and upward direction, as wellas an expander surface extending from said upper surface and inclined ina downward and inward direction; means engaging said cutter means forexpanding said cutter means laterally outward; a mandrel slidablysplined to said body and adapted for connection to a drill string; aretainer member on said mandrel movable downwardly with said mandrelalong said body to place a longitudinal surface of said retainer behindsaid abutment member to prevent inward m vement or'saidwutterrriam'fromits fuireut- Ward expanded fib 'sitibh; sa'l'd f'i'} I'i having 'a lowertransverse surracesiibs aintially normal to the axis ofsaid''Inafidfl'arid' engageable with the intersection of Saidaliilt'rrihffiifaces when said Cutter means is insulistafitially itsfully retracted positionfsaidiftainer mmfir having a bortidn betweenitslongitudinal surface and transverselsurfaee e'n'gageable with same;-pander surface to ii'rgesai'd 'cutte'r'me'a'ns out- Wardly, upondownwardmovemem of Saidmandrel along sai'd'bodyfwhen said cutter meanshas been parfiauyexpanded by said expander means.

8. In a rotary 'welfdrilling' bitz 'a' mambod cutter means mo'u'fiteddnf's'aid body and hailin an abutmentmeinbrffilfovided with'an upperedge; means engaging'saidffitterhieafis for expanding saidcu't'tenmeari's lat ally'foutwar'dfa mandrel slidabl'y 's'plined tosaidway'anaaaaptd for conneotion'to'a drill smug; aretaiiier'niemher onSaid mafidi"e1 ifi6liab1ewith aid ifiahdiel in one longitudinal'di'reetionalong "said 5663 into holding engagement with said awfmentmember to prevent iriWard'nioven'rentof said amter means from' its'dutwardsgpanaea Dos'ition; said retainer member havnigamwrtrafisversesurface" substantially; "mariner to the "aiii's 'f said mandrel andengagable in'll'n'e eontabt'withs'aid upper edge or 'saidfablutmnt membeIo'rior "to disposition of'said'retairier rii'nr'iber jl'idld'in'gengagement "with said abutment "member, to

12 transmit a 'i'esultantforde' b'etweensaidmembei-s havingsubstantially no lateral" component tendiing to urge'said cutter meansoutwardly. v I

9. Ina rotary well drilling bitz'a'mai'n' body; cutter means mounted onsaid body andhaving anabutment member; means engagingsaid hue ter meansfor expanding said cutter means laterally outward; a mandrel slidablysplined to saidfbody and adaptedfor 'eo'r'm' "t"o'n tof'a drill string;a"i"et-airier 'ifiinljronsald manarerm'evable 'withsaid friafidfrin ohjerehgituaifim d i-. rectioh 'alo'ngs dl ody toholdingerigamnt with saidabutment me g tact With 'said' dg'effiriof'to "dispositioniofretainer'ihinbr 'ntb lriolelinglz gen'l''r'ltfi'rilth said abutment minber, 'tdtranSn'iit "a resultant forcebtw'n 'said'r'iieiiibersliav'ing's'ubfs'tantially no lateral 'edmpbfi'nt' tendiiiglo urge said"Gutter means outwardly.

ARCHER;*W. KAMME-RER.

Number Name Da-te 2,466,991 Kammerer Apr. 12-1949

